Means for starting and operating motor generators



.I. C. LINCOLN.

MEANS FOR STARTING AND OPERATING MOTOR GENERATORS.

A APPLICATION FILED MAY 29, I9I7- RENEWED FEB. 25, I922. 1;41s,747.

Patented Apr. 25, 1921 .IE'IEvl. 2 MEETS-SHEET 1.

I. C. LINCOLN. I MEANS FOR STARTING AND OPERATING MOTOR GENERATORS.

APPLICATION FILED MAY 29, I917. RENEWED FEB. 25, 1922.

Patented Apr. 25, 1922.

2 SHEETSSHEET 2.

1 UNITED STATES PATENT OFFICE.

orn crmcom or LEVELAN .03 5 10 1 1. T0 THECITIZENS SAVINGS AN TRUST coMrANY; or onnvnnnnn, OHIO, A CORPORATION or OHIO.

MEANS FOR STARTING AND OPERATING MOTOR GENERATORS.

Specification of Letters Patent. Patented Apr, 25,

Application filed. Hay29, 1917, Serial No. 171,850. Renewed February 25, 1922. Serial No. 589,290.

windings in series relation until substantially normal speed is attained and there after connecting said windings in the normal series shunt operating relationship.

My said invention contemplates ,a means in addition :Whereby all unnecessary iron is cut out ofathe, field structure to obtain a machine of light .weight; the iron being disposed to prevent reversal of polaritylor flash-over through throttling the flow of magnetic lines in certain portions ofthe fields.

My invention is particularly adapted for use in connection with a portable motor converter designed for use upon street vrailway the structures featured, except as the samev lines and I may explain the same as :thus specifically .aippl-ied, although it should be understood that m invention is not restricted to. the particular use recited nor to 'm y'jbe limited by the -.claims.

This invention may be explainedv in connection with wherein e Fig. lis a diagrannnatic view-showing the -.pre:fierred circuit arrangement :for practioing my invention;

Fig. 2-is a-plan view of a suitable switch;

mechanism.

Eigs.i3 and 4 are tragmentaryviews Ethereof illustrating its interlocking means.

Fig.f5.is a lviewzof said switch mechanism in side elevation, and Fig. 6 is a viiewvof-the field :structureof the motor converter.

Throughout the, several :figures ,of the drawings, lahave employed the same character Qfrl'BfGI'GHCG to indicate similar-parts.

:R-efer-ring first to ig. $1. the .oonvential symbols will indicate to those skilled in the art, a motor converter or nmotor generator adapted to @be operated for producing an arc of low voltage through a ground circuit "ill GI- lminating respectively in acarbon and the "Tall to :be operated upon. :Gurrent preferthe accompanying drawings .abjly is taken from the trolley circuit for driving the motor.

The field structure preferably is integral and offour pole type within which rotates thearmature provided with two windings. The motor windings commonly will be designed for a current of 500 volts while the generator windings may advantageously be proportioned to produce ,70 volts. It will he understood that said windings upon the armature will be insulated from each other. Similarly there are provided two field windings which normally are in series and shunt relation respectively with the motor and generator circuits. The usual controlling resistance grids and ammeter are employed ;ior regulatingthe low voltage circuit.

With these general features in mind, I may now reter to the diagram of Fig. 1 which shows the apparatus ifor practicing my method in its normal operatingi'elation.

In starting, however, both the switches 1 and .2 are open and preferablyware so constructed that they must be closed in the order named. Assuming that said switches both are open, it will be seen from the dia gram that all ;of the motor and generator windings are in series relation. Current is taken from the trolley circuit and @passes through fuse f, conductor 3 and the high yoltage windings it of. the motor, ithence through the series field windings s to the base a of switch 2, starting resistance 1, conductor Lino-voltage release-coil 1%,.conductor :5, shunt field coils 8 low vresistance generator windings Z and conductor 6 to the ground cable .or conductor 7. 1 This connection throws all of the resistance of the shunt ,coils in series with the circuit-which servesto cut the current down materially, due to the high resistance. It

"also iurmShesv-a very strong field with a minimum current, .so that the armature is rapidly brought up to speed. When said iarmature has attained from 751% to 95% approximating-full speed, switch -1 isdepressed ithereby effecting the subdivision in these series circuits;

Tracing the course of the current again under these conditions, it will be seen that zthe operating current flows from thetrol-ley through i'use 7, conductor 3, winding h of the armature, series field windings s to the base a of switch 2, starting resistance 7', switch 1 to 60113111011 contact a, conductor 8 to the ground conductor cable 7. The speed of the armature is high enough under these conditions so that the voltage oi? the low voltage windings approximates 75-90f4 of its lull voltage and the shunt fieldss are excited by current which passes from the positive brush oi? the low voltage windings Z to contact 0 through switch 1 to the base i), thence by conductor t to the no-voltage releasecoil a, conductor 5 and the shunt field windings a to the negative brush of the low voltage armature winch ings Z.

This closing switch 1, therefore, may be said to differentiate the two circuits and place them in condition ior normal operation after the necessity for series connection has been overcome. lihereaiiter switch 2 may be closed, which merely short-ci uits the starting resistance r, leaving the circuit through the shunt field coils from the low voltage armature windings as above lc-- scribed. Switch 2 is associated with the novoltage release-coil so that it is ma ntained closed as long as current through said coil. is sufliciently strong to retain the switch against its actuating spring. Preferably, switches 1 and 2 are so inter-related that they must be closed in the order named while the release of switch 2 causes the opening of switch 1 as well.

In practice, the motor converter ordinarily is placed in condition for starting by connecting the conductors associated with fuse f in contact with the trolley wire by means of a pole, and similarly said motor converter may be stopped merely by breaking this connection with the trolley wire. However, the voltage of both armatures will continue after the motor circuit is opened, due to the inertia of the armature, as only friction reduces the speed of the armature and consequently the voltage across the low voltage armature. When the speed and therefore the voltage has dropped to such a degree that coil n is weakened sufiiciently to release switches 1 and 2 they will then return to their normal open position.

I have shown in Figs. 2 to 5, switch mech anism, by way of illustration, which is adapted to be employed in the circuit and for the purposesherein described. Minor details of the switch construction are assumed to be non-essential, since this forms no part of my invention.

The switches 1, 2 are mounted side by side upon base B; their inter-relation being secured by a cam-latch C and the electroinagnetically controlled catch D which is acted upon by windings a. Catch C is so positioned, as-shown in Fig. 4:, that the transverse rod E, mounted on switch 2, will engage its upper edge, and prevent the closing of said switch 2, as long as switch -1 is open.- Moreover, latch C is provided with a slot C adapted to be engaged by the transverse pin ll, mounted on switch 1, in oruer to move the latch into the position snown in Fig. 3, whereupon switch 2 may he closed and rod R will pass behind the latch C and hold. it and switch 1 in depressed positions long as current is maintained in windings a. This serves to at tract catch D between the poles D and holds switch 2 temporarily closed througl'i the medium of the opposite extremity of rod E. Springs G are provided. for both switches, tending constantly to throw them to their open positions and acting thus iminedizutely upon the release oi catch l).

'l 'lie arc current of the low voltage wind.- ings Z may be traced from the positive brush through ground cable 7, rail. 7', car bon 7c, conductor 10 and resistance grids g, ammeter m to the negative brush oi? the low resistance windings. It will. be understood that the amount oi current through the are established between carbon and rail may be regulated by moving the adjus able contact 7n controlling the resistance grids, in accordance with the voltage of the trolley circuit.

As stated, the field structure preferably is made as light as possible in order to adapt it better to the purposenamed. The mass of iron is so disposed as to throttle the low of magnetic lines in certain portions thereof. Preferably said field structure is built up from laminations, having the general contour exhibited in Fig. 6, wherein the central circular portion d represents the armature space about which are disposed the "four openings 6 for accommodating the field coils d partly indicated by dotted lines.

it will be observed that the approximate s c" o! the field poles are deeply cutaway that the body of iron not only is materially. reduced but n addition, a marked throttling effect on the magnetic lines is obtained] in these four localized. areas. While the structural reason for this nisposition of iron'isiound in. the material reduction in weight, coupled with the pro vision oi integral. laminae, the magnetic ell feet requires some further explanation.

Normally, the magnetic poles of the machine will be induced by the field windings as indicated by the letters N. S. N. S. in Figure 6. i

This machine, however, is in use on street carlines where the voltage is liable to increase as much as 200 volts instantaneously. hen the voltage increases, the speed of the armature has to increase proportionately to provide the necessary counter electroniotive force. During the time that the speed of the armature is increasing, very large currents pass through the armature. These large currents in the armature produce armature poles at the points N S N S. These armature poles produce a ilrosss flux on the magnetic poles N. S. and

This cross flux is reduced by the removal of the parts of the field ring, and any cross flux which exists must pass through the narrow part of the pole pieces in the mid die of the main induced pole. Removing the iron from the middle of the four induced poles, does not interfere with the flux might become great enough to cause violent sparking of the brushes and flashovers from one brush to the other, around the commutator and it is to lessen the chance of these 'flashovers that the iron back of the induced poles is removed.

Having now described the preferred method of my invention, and the means for placing it in operation, I claim asnew and desire to secure by Letters Patent, the following The combination of a dynamotor having the-motor field and armature windings separate from the generator field and armature windings, and switching mechanism adapted to connect all of said windings in series relationship while starting, and to connect said generator windings in shunt relationship with said motor windings when approximately normal speed has been attained.

In testimony whereof I do now afiix my signature in the presence of two witnesses.

JOHN C. LINCOLN.

WVitnesses FRANK BUBUA, r ALBERT LYNN LAWRENCE. 

